David Lazarus runs down the top consumer stories of the day on KTLA-TV Channel 5.

David Lazarus runs down the top consumer stories of the day on KTLA-TV Channel 5.

CaptionAddition of tech giant seen as making the index more diverse

David Lazarus runs down the day's top consumer stories on KTLA-TV Channel 5.

David Lazarus runs down the day's top consumer stories on KTLA-TV Channel 5.

Caption'Handling' fees add up for consumers

David Lazarus runs down the day's top consumer stories on KTLA-TV Channel 5.

David Lazarus runs down the day's top consumer stories on KTLA-TV Channel 5.

CaptionForbes says there's a record number of super-rich worldwide

David Lazarus runs down the top consumer stories on KTLA-TV Channel 5.

David Lazarus runs down the top consumer stories on KTLA-TV Channel 5.

CaptionPhone and cable companies set for years of litigation

David Lazarus runs down the day's top consumer stories on KTLA-TV Channel 5.

David Lazarus runs down the day's top consumer stories on KTLA-TV Channel 5.

Such requirements vary from state to state. But there are some factors that will apply to all purchases of new cars.

First of all, the dealer will want to run a credit check to see if you qualify for financing. Even if you have no intention of financing the car, they'll still want to make the pitch. And to do that, they'll need your Social Security number.

But that's not the main reason why you'll likely have to give it to them.

The main reason is that almost all financial transactions worth $10,000 or more have to be reported to the Internal Revenue Service, and the dealer will need your Social Security number for that.

While the IRS, weirdly, doesn't consider a personal check to be cash, the dealer almost certainly won't take a check without making sure you're good for the money.

You can refuse to authorize a credit check, regardless of how hard the sales rep pushes. But if your new car is worth more than $10,000 -- and it likely is -- you won't have any wiggle room when it comes to your Social Security number.